This project has established a database for comparative neuroanatomy of primates using high resolution magnetic resonance imaging (MRI). A total of 44 animals were scanned, including representatives of every species listed above and all of these scans have been reconstructed to provide surface rendering and volumetric measures. Digitized versions of these scans have been stored on compact disc for distribution to investigators interested in primate brain evolution. Our own analysis has demonstrated 1) a decrease in relative cerebellar volume in humans compared to apes; 2) a decrease in relative corpus callosum size in the human brain; and 3) a relative increase in intra-hemispheric projections in the human brain. These studies provide the first MRI database for studies of comparative primate brain evolution and should yield novel insights into differences between human and non-human primate neuroanatomy. FUNDING MacArthur Foundation $40,000 9/01/96 - 2/28/98 Leakey Foundation $ 7,500 1/01/97 - 12/31/99 PUBLICATIONS Rilling, J.K. and Insel, T.R. Differential expansion of neural projection systems in primate brain evolution. NeuroReport (In press). Rilling, J.K. and Insel, T.R. Evolution of the cerebellum in primates Differences in relative volume among monkeys, apes, and humans. Brain, Behavior and Evolution 52:308-314, 1998. Rilling, J.K. and Insel, T.R. The primate neocortex in comparative perspective using magnetic resonance imaging. Human Evolution (In press). P51RR00165-38 1/1/98 - 12/31/98 Yerkes Regional Primate Research Center